
Overtone spectrum of SiH stretching in H_{2}SiCl_{2}
Chen Ping, Zhu Huai, Hao LuYuan, Hu ShuiMing, Liu AnWen, Zheng JingJing, Ding Yun
Chin. Phys. B, 2005, 14 (3):
634641.
DOI: 10.1088/10091963/14/3/037
The overtone spectra of H_{2}SiCl_{2} molecule in the regions of 2000—9000cm^{1} and 12000—12900cm^{1} at room temperatures have been studied by use of highresolution Fourier transform spectroscopy and sensitiveintracavitylaser absorption spectroscopy, respectively. The variations of vibrational quantum numbers ΔV_{SiH}=1, 2, 3, 4 and 6 for the overtones of the SiH stretching have been analysed and assigned with the local mode model and the normal mode model. The values of harmonic frequency ω_{m}, anharmonicity constant χ_{m}, bond coupling constant λ, the Morse oscillator parameters D_{e}, α, and interaction force constant f_{rr′} are derived from the experimental spectrum with nonlinear leastsquares fitting. The most striking feature of the SiH_{2}Cl_{2} is that the larger the vibrational energy, the smaller the energy difference between a couple of lowest stretching states of a given manifold, and finally, the couple of lowest stretching states are degenerated within the experimental error for ΔV_{SiH}≥4 vibrational manifolds. The degenerate energy level structure resembles that of a diatomic Morse oscillator; the transition energies show a remarkable fit to the Birge—Sponer relation. The high vibrational states can be described straightforward with a SiH diatomic Morse oscillator wavefunction, this is an indication of vibrational bond localization.
